Service worker registration

server-worker.js

// main.js
if (!('serviceWorker' in navigator)) {
  console.log('sw not supported');
  return;
}

navigator.serviceWorker.register('/path/to/service-worker.js') // returns a Promise
  .then(function(registration) {
  console.log('SW registered! Scope is: ', registration.scope);
});
//------------------------

// service-worker.js
// Events: install, activate, message, fetch, sync, push...
self.addEventLister('activate', function(event) {
  // Clean up stale sw's
});

self.addEventListener('fetch', function(event) {
  event.respondWith(
    caches.match(event.request)
   )
});
//------------------------